598 TRANSACTIONS OF SUB-SECTION K. 



' weak ' plants from second generation cultures grown by Professor Biffen from 

 the following crosses: Polish xRivett, FifexRivett, Fife x Rough Chaff. 



The authors aro at present engaged in standardising the method more com- 

 pletely. They take this early opportunity of publishing a preliminary note, since 

 methods of picking out ' strong ' and ' weak ' individual plants are so urgently 

 needed. 



3. The Effects of Ventilation on the Temperature and Carbon Dioxide of the 

 Air of Byres. By James Hendrick, B.Sc. 



It is firmly believed among dairy farmers in, at any rate, many parts of the 

 country that it is important to keep the byres warm if dairy cows are to give 

 a full flow of milk. It is not economical to maintain the temperature in winter 

 by artificial heating, and in order to keep it up by the heat of the animals them- 

 selves it is usual for fanners to restrict the ventilation, especially in byres where 

 the cubic capacity per animal is great. The temperature is thus maintained by 

 keeping in the warm polluted atmosphere, and the colder and more boisterous the 

 weather the more the circulation of air is restricted. 



The author was associated with the late Mr. John Spier, Newton Farm, 

 Glasgow, in carrying out experiments on the ' Influence of Temperature on Milk 

 Yield.' In experiments carried on during the winters 1908-09 and 1909-10 cows 

 were divided into two lots, and one lot was kept warm by restricting ventilation 

 in the usual way, while the similar byre in which the other lot was kept was 

 well ventilated, no matter what the temperature fell to. In each winter the expe- 

 riment was carried on at five different centres. In 190S-09, 100 cows were under 

 experiment, and in 1909-10, 104 cows. 



Temperature records for all byres were continuously kept during the whole 

 course of the experiments. In order to measure the pollution of the air the 

 carbon dioxide gas was determined periodically. The average temperature for 

 the whole period, November to March, was in 1908-09, in the byres with re- 

 stricted ventilation, 59-4° F., and in the freely ventilated byres 49"S° F. ; and 

 in 1909-10 in the byres with restricted ventilation 57"3° F., and in the freely 

 ventilated byres 49-0° F. 



The carbon dioxide found is shown in the following table : — ■ 



Parts of C0 2 per 10,000. 



The carbon dioxide in the byres with restricted ventilation is on the average 

 nearly twice as high as that in the freely ventilated byres. In both cases 

 great variations were found between different samples. In neither case was the 

 air on the average very pure, but in many cases the impurity, as indicated by the 

 carbon dioxide, was very serious in the byres with restricted ventilation. 



The byres used in these experiments were distinctly above the average of 

 the dairy byres of the country in average space per cow, in ventilation, and in 

 general appointments. It may, therefore, safely be concluded that the impurity 

 of the air shown in the byres with restricted ventilation is not greater than 

 that which prevails in the ordinary dairy byres of the country. During these ex- 

 periments the milk yield was as great in the freely ventilated as in the badly 

 ventilated byres, and the health of the cows was better in the freely ventilated 

 byres than in the others. Attempts were made to measure the bacteriological 

 pollution of the atmosphere, but on account of the difficulties which arose these 

 had to be abandoned. 



These experiments indicate that it is more important to have fresh air in 

 byres than a large cubic space per cow. 



